Compound photoelectric conversion devices having a semiconductor thin film as a light absorbing layer have been developed. In particular, photoelectric conversion devices having, as a light absorbing layer, a p-type semiconductor layer with a chalcopyrite structure have high conversion efficiency and thus promising applications. Specifically, photoelectric conversion devices having a light absorbing layer of Cu(In,Ga)Se2 as a Cu—In—Ga—Se (CIGS) compound have relatively high conversion efficiency.
A photoelectric conversion device has a p-type Cu—In—Ga—Se semiconductor layer as a light absorbing layer. Such a photoelectric conversion device generally has a structure including a soda-lime glass substrate, and a Mo electrode layer, a p-type semiconductor layer, an n-type semiconductor layer, an insulating layer, a transparent electrode, a top electrode, and an antireflective film, which are stacked on the substrate. Such a high-efficiency CIGS photoelectric conversion device is designed to have a homojunction structure in which the p-type semiconductor layer has an n-doped part in the vicinity of the upper transparent electrode. The n-doping is performed by a treatment in a solution after the p-type semiconductor layer is formed by vapor deposition or the like. In the solution treatment, peeling can easily occur at the interface between the p-type semiconductor layer and the Mo electrode layer. It is known that when a CIGS light absorbing layer is deposited on a Mo electrode layer, a c-axis-oriented MoSe2 layer is formed at the interface between them. The MoSe2 layer can easily undergo delamination because of its weak van der Waals interlayer coupling. It is known that a randomly-oriented MoSe2 layer is formed so that it can have improved adhesion.